Leucine, isoleucine and valine are called branched chain amino acids (BCAA) and a mixture of these three kinds of amino acids is known to have muscular fatigue recovery effect (e.g., see JP-A-8-198748). The mixture of the three kinds of BCAA has been widely used as nutrients by being made into granules or drinks, but immediately after being absorbed to the small intestine, it is relatively rapidly metabolized, and thus sustained effect on muscular fatigue recovery is unlikely obtained.
Also, nutrients comprising a whey protein or a decomposition product of whey protein or soy protein have been known, but no sustained action on muscular fatigue recovery has been known (e.g., see Gastroenterology, 7, 151-161 (1976) and Gut, 14, 494-501 (1974)).
On the other hand, as a mixed composition of the mixture of the three kinds of amino acids with a protein, a composition obtained by adding to an amino acid mixture of leucine, isoleucine and valine 2- to 30-fold amounts of a protein, followed by solidification, is also known (e.g., see JP-A-60-186261), but the protein is used only as an excipient and is not used for facilitating fatigue recovery effects.